<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>toString测试</title>

    <script>

        let i = 1;
        const a = {
            toString() {
                return i++
            }
        }

        console.log(a == 1 && a == 2 && a == 3);


    </script>
</head>

<body>

</body>

</html>